NetworkingChapter 4

Reading Quiz

Learning Outcomes• Appreciate Networking Mediums, Topologies, and necessary

Hardware• Protocols• Distinguish between different Client/Server Relationships• Understand SSH & X Protocol uses• Expose to VCL

Client/ Server Relationship• Server• A powerful machine dedicated to governing access to

information, common type web server, however there are more, databases, files, email & printers

• Client• A normal PC where applications run and access information off of

a server• AFS Connection• You are the Client, AFS is the Server

Network MediaWired Connections• Twisted Pair Cable• Most common media to physically connect two devices together,

incorrectly referred to as “Ethernet cable”, contains several pair of cables twisted around one another, maximum range 100m

Only two pairs are used, unless you are running Gigabit ethernet

Network MediaWired Connections• Coaxial Cable• Single copper conductor at its center, a plastic layer provides

insulation & a braided metal shield, which block interference. Maximum range 500 m

Network MediaWired Connections• Fiber Optic Cable• Uses pulses of light that travel up to the speed of light to transfer

data great distances. • Uses translucent fibers, normally glass or plastic, then coated by a

plastic coating and kevlar fibers to provide strength, finally PVC surrounds outside, max range 145 km (90 mi)

• Primary choice for telecommunication industry

Network MediaWireless Connections• Wireless communications use RF (radio frequency) to

broadcast a signal between a wireless client and a base station or two wireless clients

• Due to the 802.11 standard networking computers is simple now

Networking Media802.11 breakdown• 802.11• Wireless LAN access providing 1 or 2 Mbps in the 2.4 GHz band

• 802.11a• Provides speeds up to 54 Mbps in the 5 GHz band, standard used in

NC State classrooms, was not consumer cost effective• 802.11b• Provides speeds of 11 Mbps, with a fallback to 5.5, 2 &1, in the 2.4

GHz band• 802.11g• Provides speeds of 20+ Mbps in the 2.4 GHz band, current NC State

wireless access as a whole• 802.11n• New extension to 802.11 approved in Oct 2009, using two antennae

to provide speeds up to 150 Mbps, rivaling Ethernet speeds

Networking MediaWireless Fun Facts• MIMO (Multiple-Input and Multiple-Output)• A new “smart antenna” using multiple antenna to the receiving and

transmitting end to boost effectiveness. • Bluetooth• Allows short ranged connection between two devices, normally devices that

want to connect to a computer, operates in 2.45 GHz band at 10-100m. • Bluetooth 2.0 allows speeds up to 2.1 Mbps• Bluetooth 3.0 allows speeds up to 24 Mbps

• Cell Phone/WiMax• The G standard is used to provide Telecommunications access to cellphones

• 3G minimum speeds of 200 kb/s• 4G minimum speeds of 100 Mb/s up to 1 Gb/s

• WiMax• Using existing cellphone towers and signals, the 802.16 standard is trying to

become the first national broadband system with speeds being updated to 1 Gb/s

Network Topology• LAN (Local Area Network)• Small network consisting of nodes, computer & other network

devices, used to segregate larger networks into manageable pieces

• WAN (Wide Area Network)• Industries own/maintain these geographically larger networks

than LANs, how Time Warner Cable provides internet access• Fiber to Node: Fiber optic cable is run to a centralized node which

splits it into multiple connections to be send out separately

• MAN (Metropolitan Area Network• A mix between LAN & WAN normally used by an ISP to connect

several offices together.• Uses a mix of routers & specialized switches

Types of Networks• Star Network• Based off of a concentrator, which is a single device that manages

the network, also acts as a repeater, strengthening the signal over the network.

• Useful network type because if one node fails it doesn’t stop the flow of traffic, however if the concentrator fails the entire network goes down

• Examples of concentrators are routers or switches

Types of Networks• Tree Network• Groups a lot of Star Networks together and is managed in a

hierarchal manner, with the node above the current one having to handle more traffic than the previous one

Types of Networks• Bus Network• Set of clients connected via a single shared connection line

known as a bus• Advantages

• Easiest and cheapest to implement and extend• To add a device you just simply need an interface card and a free

node• Disadvantages

• A line break will cause the entire network to go down• Limited number of connections can be made before the network will

slow to a crawl

Types of Networks• Ring Network• Each node has two neighbors, easy to add devices since all

devices have equal access, however to send information, the packet has to be sent through each node until it reaches its desired recipient

Establishing a Network Connection• Protocols

Layer Example

Link Layer Ethernet

Internet Layer Internet Protocol (IP)

Transport Layer Transmission Control Protocol (TCP)

Application Layer HyperText Transfer Protocol (HTTP)

Each protocol adds an extra level of abstraction on top of the last, this prevent duplication

Application

Transport

Internet

Link

Establishing a Network Connection• Obtain an IP address • It’s like your home address but for your computer,

some network use a Dynamic Host Configuration Protocol (DHCP) to automatically assign an available IP address• IPv4 uses 32 bit address to assign access with a

maximum of 4,294,967,296 unique addresses• IPv6 is the only solution to the inevitable

exhaustion, which uses 128 bit address and can assign up to 3.4 x 1038 addresses, however IPv4 & IPv6 are not directly compatible which is why people are slow to transition

Establishing a ConnectionTricks• NAT (Network Address Translation)• Allows all computer connected to a router to use a

single public IP address, while the router assigns its own private IP address to it’s clients

• DNS (Domain Name System)• Allows you to use a domain name instead of an IP

address, so instead of typing in the actual IP address to Google’s search engine server you just type www.google.com• DNS servers keep track of the Domain Names and

their corresponding IP addresses

Home Network

SSH• Encryption is what makes SSH impervious to attacks from

outside the network• Tunneling is the means to transfer the encrypted packets

X Protocol• A special type of client/server relationship on the same

computer• The X Protocol program acts as the server, while individual

applications at as the client• Applications & input devices tell the X Server what to display

and the X Server sends the monitor what should be shown.

RDP

• Remote Desktop Protocol• Allows resources to be accessed from any machine

running Microsoft Terminal Services• Achieves this by using separate tunnels to send

different pieces of information & instructions so that the client can receive, decode, and create a smooth connection to the remote computer

P2P• Peer to Peer • Used by most torrent sites, a peer to peer connection is when a

group of computers on a network simultaneously send and receive information from one another.